1. Field of the Invention
The present invention relates to a magnetic tape cassette such as a video tape cassette.
2. Description of the Prior Art
FIG. 1 and FIG. 2 are schematic views of the conventional magnetic tape cassette wherein reels (4), (5) holding a wound magnetic tape (3) are positioned in a casing comprising an upper half casing (1) and a lower half casing (2) and tape guides (6), (7), (8) for guiding the magnetic tape (3), and a tape pad (9) are provided in the running path of the magnetic tape (3) between the reels (4), (5) so that the magnetic tape (3) can move continuously in contact with these elements (6) to (9) to be wound on the reel. The reference numerals (10) and (11) designate guide poles.
In the conventional magnetic tape cassette, the tape guides (6) to (8) made of stainless steel are coated with a hard chrome plating or a nickel plating or are subjected to surface-grinding to reduce their frictional resistance to the magnetic tape (3) so as to assure a smooth running of the magnetic tape (3). However, the smooth running of the magnetic tape is sometimes prevented by a load applied when winding the magnetic tape, due to the frictional resistance of the tape guides (6) to (8) to the magnetic tape (3) even though one of the above described surface treatments is applied to the tape guides. Especially, when a winding torque of a tape deck is small or when the magnetic tape (3) is wound under tension in a case of a rapid feeding or a rapid returning from the stopped state or in a case of a rapid feeding or a rapid returning from the recorded picture-reproducing state, the magnetic tape comes into close contact with the tape guides so that the static frictional coefficient is high. Thus, a large load is applied to the magnetic tape (3) to prevent the winding of the magnetic tape (3) resulting in non-running of the tape. This phenomenon occurs depending upon environmental conditions such as surface property of the tape guides, temperature and humidity which occasionally causes the running trouble of the magnetic tape.